Look-ahead branch detection system



1970 ca. c. DRISCOLL. JR

LOOK-AHEAD BRANCH ISETECTION SYSTEM 30 Sheets-Sheet 1 Filed Jan. 15,1968 INVENTOR GRAHAM C. DRISCOLL, JR.

mJOmFZOO 30528 249 2:55am E05: 24m :5 M22683 5255 mm; 32 2 v63 momwuoommE 225352. .zzsa :32.

62-02mm m0. WJOFPZOU ATTORNEY Dec. 29, 1970 Filed Jan. 15. 1968 G. C.DRISCOLL. JR

LOOK-AHEAD BRANCH DETECTION SYSTEM 30 Sheets-Sheet 2 FIG. FIG. 2

FIG. FIG. FIG. FIG. FIG. FIG. FIG.

FIG. FIG. FIG. FIG. F16. 1-10.2

2J 2K 2L 2M 2N F|G.2A 11mm msmucnou REGISTER 10o 'MMED'ATE Z 1111PROCESSOR) A5 COMPAR'SGN [0Pc001-:[ FROM] TO [101010101010 k A v J (1- IH8 f i- 5 015000511 ADVANCE 1011111101 411111011 'fBRANCH i06 M A END MA 104 '1 m A 1 A4 -A2 I I 116 -\-ENTER BRANCHFF A4- 0 1 0 122 A6 L I5 A5I2 1! Dec. 29, 1970 c, msco L, JR 3,551,895

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet 5FIG. 2B

Dec. 29, 1 970 7 s. c. DREQLL. JR 3,551,895

LOOK'AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet 5K ZEROS H Li 1 /i88 G SET 10'1'11111F11 PROCESEDR 1 FINISHES EXECUTION 0ET BY SYSTEM AN INSTRUCTION S on P1 1 5 *PT I I FIREOUEST FF 1 6 f"START FF P34 1 o 1 o P2 6 P9L 1 21 I P34 m F F NEXFTFCYCLE F1a- LI7 1 Jo J 15 M6 9,: REQUEST ADDRESSES -11 M w FF |40-- G 1 0 123 A 144 F15 II6 3 I I RE'QUEST ADDRESSES REGISTER ADDRESS 0F 6 m: FIRST11151110011011 Dec. 29, 1970 Filed Jan. 15, 1968 G. C. DRISCOLL. JR

LOOK-AHEAD BRANCH DETECTION SYSTEM 30 Sheets-Sheet 6 3 m H I 1 f r A N aPI "*h 1 i o ADDRESS INSTRUCTION s 212 P5 s 270 g T0 PROCESSOR 3 Imsmucnon REG 1 2 :s M i g mi (r" 1 f A i g Pl1 1 1 o ADDRESS INSTRUCTION-ss i 1 1' g A a, J

1 P8 k: e w J I P12-- 6 was 5 mi cm 226 l n L llift PSj f mo ADDRESSINSTRUCTION sss I W4 5 Y J v G J 192 T0 msmucnon P80 G P 1 FETCHMECHANISM 1 P1 1970 s. c. DRISCOLL. JR 3,551,395

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet 7FIG. 2F

I O ADDRESS MASK INSTRUCTION 58 DECODER FROM GATE 228 FROM GATE 290 FIG.2.] FIG. N

H 200 P9 OR I O ADDRESS MASK INSTRUCTION I O ADDRESS INSTRUCTION 1970 G.c. DRISCOLL, JR 3,551,395

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet 8FIG. 26

FROM GATE 292 FROM GATE FIG. 21 3"! FIG. 2.!

Pi Pl P9 0R P9 i O ADDRESS MASK INSTRUCTION 1 O ADDRESS INSTRUCTION Dec.29, 1970 G. C. DRISCOLL. JR

Filed Jan. 15, 1968 30 Sheets-Sheet 9 I FIG. 2H J u A l r q A i P11 Aoscooea 1 OADDRESS MASK m P28 1 W P30 J G j I P29- \m 1 ALL ONES 0 F i1la-L: P30} x a T0 PROCESSOR G :3 11151 REG 21a 1 o ADDRESS ms'mucnow J 1v J V i P24 s H 1 1 1 G -P51 l l k: I I

FROM cm 520 mom cm 544 L FIG. 2.] F|G.2J "206 P1 P1-- 208 I 519 w P9 0Rn B8B k l (A 1f 1 1 o ADDRESS MASK INSTRUCTION 1 o ADDRESS msmucnow k Pw J L 5 v J 6 P310 PSKJJ 1 A x y 1 J 1y r A Y Dec. 29, 1970 c, p scoL JR3,551,895

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet1O 6 230 L I P20 P21 A G P24 2.12 I P20 P25 A G P26 34a I P20 I P2s I GP20 1 o ADDRESS MASK INSTRUCTION BB DECODER Mu ONES J) 550 ll I FROM cm546 ALL ZEROS FIG. 21

1 O ADDRESS MASK INSTRUCTION Dec. 29, 1970 Filed Jan. 15,

LOOK-AHEAD BRANCH DETECTION SYSTEM G. C. DRISCOLL. JR

30 Sheets-Sheet 1 1 ADDRESS 2 ADDR\ESSI :aBSS

==BBS G EDBBB FIG. 2d

Dec. 29, 1970 c, 5 JR 3,551,895

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet18 I0 msmucnou men MECHANISM A? FIG. 2K IG V 2sa oecoosn ALL ONES ,lmZ6165 244* QR I I k -*-Al JIIHA) ZLLIT-T'I! RETAIN r 1 120"\ FROM TOMASK 4 0 INTER BRANCH REGISTER g Q Dec. 29, 1970 G. c. omscoLL. JR 3,55,895

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheetl5 ZEROS 0R 1s ONES [1- CYCLE J 1:11:11] muum msxneclsm I w I2 V I8ARGUMENT REGISTER CYCLE FROM T TT L L L m USE I IS NOTE ONLY THISPORTION OF ASSOCIATE OR 19 MEMORY mu usso FOR ASSOCIATIVE PURPOSES Dec.29, 1970 G. C. DRISCOLL. JR

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15. 1968 30 Sheets-Sheet14 314, 2214 I 222 252 i 256 256 302 29s zeal A s G A A e A P18 ,124 J IRESET men I8 OR 129 -14 INDICATORS 1&1, IZ3A m" V RITE OR-I15 I4- an Egg-I2T A 111 671 A 111 HSQOR 1 fin 58 B--- 613 f w 127 T 5* 1 1 BRANCHBRANCH Assoc. ASSOCIATIVE MEMORY MEMORY CONTROL (BAM) i u.s. PATENT uls.PATENT 152 muss mu, ass

2 I8-- I23- l/ f J FF 182 EOLFF/ I a o jr Q I10 1ss s*g; FIG. 2M

Dec. 29, 1970 3,551,895

G. C. DRISCOLL. JR

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet15 A-MM Fr 1 m M n- 1 20 OR r174 w 1 I23- fi ,J film/nu mncn N 1|o CYCLEFROM TO MASK a [o] ASSOCIATIVE I ueuonv mm w 4 fr'fi 1 REGISTER m USE J115 i G -12o 1 k K M l nu I *I14 4 162 I w m y/ I DECODER /ALL cm 1 N6 5so 5 G G +118 ALL ONES J) l; 1 1h iiii my) FIG. 2N

Dec. 29, 1970 G. c. DRISCOLL. JR 3,551,395

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet16 FIG.2Q

CYCLE N 23 CTR INCREMENT 1970 G. c. DRISCOLL. JR 3,551,395

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-Sheet17 IN THE ADVANCE BRANCH INSTRUCTION JUST DETECTED,

IS THE INNEDIATE CONPARISON BIT SET TO'I? YES NO 2 HAS THE amen commonam an I NO YES FORCE THE BRANCH TO TAKE PLACE I TREAT AS ANUNCONOITIONAL BRANCH) IS THERE A PREVIOUS ENTER BRANCH OPERATION NOW INPROGRESS 7 NO YES REQUEST AN ENTER BRANCH OPERATION 6 PROCEED T0EXECUTION OF NEXT INSTRUCTION Dec. 29, 1970 G. c. DRISCOLL. JR 3,551,895

LOOK-AHEAD BRANCH DETECTION SYSTEM Filed Jan. 15, 1968 30 Sheets-SheetIO ADDRESSES i, FIG. 6

"* ADVANCE amcn FROM n44 T0 HHS-RETAIN wrou- N+9 IMMEDIATE common an M0"UFF N*II II+I2 IIIS II+I4 /ADVAIICE BRANCH II I5 FROM II+I8 T0II+4'RETMII I!|T"0FF" II+I6 IMMEDIATE COHPARISUII BIT +17 "IIII" IIIBIP19 IP20 TABLE OF CONDITIONS UNDER WHICH THE VARIOUS REGISTERS IN LEVEL3 OF THE LOOKAHEAD TREE RE- QUIRE FILING REGISTER a REGISTER sa REGISTERas MASK FIELD MASK FIELD MASK FIELD NOT ALL"IS" NOT ALLI'S 253 um m'ws'HOT m'o's" 32 g) NOT ALL "0's" um ALLIS' 333} um ALLO'S" NOT Im'o's FIG.7

